1. Field of the Invention
This invention relates to a rotating shaft unit, more particularly to a rotating shaft unit having two shaft sections, which can be located selectively at a relative angular position.
2. Description of the Related Art
Referring to FIG. 1, a conventional rotating shaft unit 1, which is used to interconnect a keyboard unit (not shown) and a monitor unit (not shown) of a portable computer (not shown), is shown. The conventional rotating shaft 1 includes a first shaft section (1A) and a second shaft section (1B). The first shaft section (1A) includes an internally splined first sleeve 11 and a first plug 13, which has an outer end surface that is formed with a cylindrical axial bore 131. The first plug 13 is externally splined to engage fittingly the first sleeve 11, thereby preventing rotation of the first plug 13 within the first sleeve 11 while permitting axial movement of the first plug 13 within the first sleeve 11. A right coupler plate 16 is fixed on the first sleeve 11, and has a mounting portion 161, which is adapted to be coupled with the keyboard unit (not shown). The second shaft section (1B) includes an internally splined second sleeve 12 and a second plug 14, which is externally splined to engage fittingly the second sleeve 12. Similarly, the second plug 14 can move axially but is not rotatable within the second sleeve 12. The second plug 14 has an end surface, which is formed with a bore 141, in which a spring 142 is disposed between the second plug 14 and a left end wall of the second sleeve 12. The second plug 14 further has an integral tongue 143, which extends movably into the bore 131 in the first plug 13. A left coupler plate 17 is fixed on the second sleeve 12, and is adapted to be coupled with the monitor unit (not shown). The first and second plugs 13, 14 are formed respectively and integrally with opposed annular tooth units 15. The spring 142 is in a compressed state to engage the annular tooth units 15 so as to prevent relative rotation of the first and second plugs 13, 14, thereby positioning the monitor unit (not shown) relative to the keyboard unit (not shown). The first and second plugs 13, 14 can be disengaged forcibly from each other to permit rotation of the monitor unit (not shown) relative to the keyboard unit (not shown). When it is desired to adjust the position of the monitor unit (not shown) relative to the keyboard unit (not a shown), the operator must force the annular tooth units 15 to disengage upon rotation of the monitor unit (not shown) relative to the keyboard unit (not shown), thereby resulting in energy consumption and inconvenience during the adjustment process.
The object of this invention is to provide a rotating shaft unit in which the relative angular position of two interconnected shaft sections can be adjusted easily in an energy-saving manner.
According to this invention, a rotating shaft unit is adapted to interconnect a first object and a second object. The rotating shaft unit includes a first shaft section with a first sleeve adapted to be fixed on the first object, and a second shaft section with a second sleeve adapted to be fixed on the second object. A fixed plug is secured within the first sleeve. A movable plug is disposed axially and movably within the second sleeve. Each of the fixed plug and the movable plug has an integral annular tooth unit. A radial push rod extends movably into the first sleeve and the fixed plug, and is located at a retracted position. A radial resilient element biases the radial push rod to move outwardly in the first sleeve and the fixed plug. An axial push rod is fixed on the movable plug, and extends movably through the fixed plug and the first sleeve. An axial resilient element biases the axial push rod to an extended position, in which the annular tooth units engage each other to secure relative angular position of the fixed plug and the movable plug. When the axial push rod is pressed to a retracted position, the radial push rod is biased by the radial resilient element to an extended position. At this time, the radial push rod is located so as to prevent the axial push rod from axial movement in the first sleeve, thereby disengaging the annular tooth units from each other. As such, the first object can be rotated relative to the second object. After the first object is rotated to a selected position relative to the second object, the radial push rod is pressed to the retracted position so as to return the axial push rod to the extended position by the action of the axial resilient element, thereby engaging the annular tooth units. Accordingly, the relative angular position of the first and second objects can be adjusted easily in an energy-saving manner.